Objective This study aimed to evaluate the bone integration performance of antibacterial carbon dot(CD)-modified polyether ether ketone(PEEK)in infectious bone defect environments.Methods Guanidine-based CDs(G-CDs)prepared by the melting method combined with dialysis purification were used to modify PEEK implants using polyvinyl butyraldehyde(PVB)by the soaking-drying method(PEEK/PVB-G-CDs).SD rats were divided into the following groups:(1)PEEK-implanted uninfected(PEEK(-)),(2)PEEK/PVB-G-CDs-implanted uninfected(PEEK/PVB-G-CDs(-)),(3)PEEK-implanted infected(PEEK(+)),and(4)PEEK/PVB-G-CDs-implanted infected(PEEK/PVB-G-CDs(+)).A hole(diameter 2 mm,depth 5 mm)was drilled at the lateral condyle of the vertical femur in all rats to simulate a bone defect.Rats in the PEEK(-)and PEEK/PVB-G-CDs(-)groups without infection were injected with 30 μL physiological saline into the bone marrow cavity,and rats in the PEEK(+)and PEEK/PVB-G-CDs(+)groups with infection were injected with 30 μL MRSA bacterial suspension(1.5 × 104 colony-forming units/mL)into the bone marrow cavity.The implantation site was observed using animal-specific X-ray examination at 0,2,and 4 weeks after implantation,and the bone tissue characteristics of the implantation site were evaluated by micro computed tomography(CT)at 6 weeks after surgery.The bone implantation sites in each group of rats were examined by bacterial culture of bone marrow and hematoxylin and eosin staining,Toluidine blue,Goldner trichrome,and immunohistochemical staining.Results X-ray,Micro-CT,bacterial culture of bone marrow,and histopathological analysis confirmed no signs of infection in the PEEK(-)and PEEK/PVB-G-CDs(-)groups and the implants were integrated with the bone defects.Rats in the PEEK/PVB-G-CDs(+)group showed signs of antibacterial activity that effectively controlled the osteomyelitis caused by MRSA and achieved bone integration,while rats in the PEEK(+)group failed to achieve bone integration because of persistent infection.Immunohistochemical staining confirmed lower levels of anti-inflammatory factors such as IL-4 and IL-10 in the PEEK(+)group,and stronger expression of pro-inflammatory factors such as IL-6 and TNF-α compared with the other three groups,indicating that G-CD-modified PEEK inhibited MRSA infection,regulated inflammation levels in the local microenvironment,and promoted bone integration at the site of bone defects.Conclusions Antibacterial G-CDs modified PEEK exhibits excellent bone integration performance,providing a candidate strategy for future clinical treatment of infectious bone defects.

Objective This study aimed to evaluate the bone integration performance of antibacterial carbon dot(CD)-modified polyether ether ketone(PEEK)in infectious bone defect environments.Methods Guanidine-based CDs(G-CDs)prepared by the melting method combined with dialysis purification were used to modify PEEK implants using polyvinyl butyraldehyde(PVB)by the soaking-drying method(PEEK/PVB-G-CDs).SD rats were divided into the following groups:(1)PEEK-implanted uninfected(PEEK(-)),(2)PEEK/PVB-G-CDs-implanted uninfected(PEEK/PVB-G-CDs(-)),(3)PEEK-implanted infected(PEEK(+)),and(4)PEEK/PVB-G-CDs-implanted infected(PEEK/PVB-G-CDs(+)).A hole(diameter 2 mm,depth 5 mm)was drilled at the lateral condyle of the vertical femur in all rats to simulate a bone defect.Rats in the PEEK(-)and PEEK/PVB-G-CDs(-)groups without infection were injected with 30 μL physiological saline into the bone marrow cavity,and rats in the PEEK(+)and PEEK/PVB-G-CDs(+)groups with infection were injected with 30 μL MRSA bacterial suspension(1.5 × 104 colony-forming units/mL)into the bone marrow cavity.The implantation site was observed using animal-specific X-ray examination at 0,2,and 4 weeks after implantation,and the bone tissue characteristics of the implantation site were evaluated by micro computed tomography(CT)at 6 weeks after surgery.The bone implantation sites in each group of rats were examined by bacterial culture of bone marrow and hematoxylin and eosin staining,Toluidine blue,Goldner trichrome,and immunohistochemical staining.Results X-ray,Micro-CT,bacterial culture of bone marrow,and histopathological analysis confirmed no signs of infection in the PEEK(-)and PEEK/PVB-G-CDs(-)groups and the implants were integrated with the bone defects.Rats in the PEEK/PVB-G-CDs(+)group showed signs of antibacterial activity that effectively controlled the osteomyelitis caused by MRSA and achieved bone integration,while rats in the PEEK(+)group failed to achieve bone integration because of persistent infection.Immunohistochemical staining confirmed lower levels of anti-inflammatory factors such as IL-4 and IL-10 in the PEEK(+)group,and stronger expression of pro-inflammatory factors such as IL-6 and TNF-α compared with the other three groups,indicating that G-CD-modified PEEK inhibited MRSA infection,regulated inflammation levels in the local microenvironment,and promoted bone integration at the site of bone defects.Conclusions Antibacterial G-CDs modified PEEK exhibits excellent bone integration performance,providing a candidate strategy for future clinical treatment of infectious bone defects.